new liberty project - avesoro · –pit design and optimisation –calculation of reserves ......
TRANSCRIPT
![Page 1: New Liberty Project - AVESORO · –Pit design and optimisation –Calculation of Reserves ... •Stripping ratio = 15.5:1 •Mining cost $3.06/t mined* •Gold produced = 859koz](https://reader030.vdocuments.us/reader030/viewer/2022040909/5e824bb8fe742e6c0a50b16f/html5/thumbnails/1.jpg)
Aureus Mining New Liberty Project
Mining
February 2014
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Contents
• Geotechnical
• Pit optimisation
• Pit design
• Mining Contractor
• Groundwater management
• Water management
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AMC input on: – Updated Geotechnical assessment – Pit design and optimisation – Calculation of Reserves – Development of High level production schedules – Design of ROM Pad – Design and sequencing of Waste Rock Dumps
• RPS Aquaterra input on: – Surface water assessment and pumping recommendations – Pumping tests on monitoring boreholes – Groundwater assessment and – Development of groundwater model
• Knight Piesold input on:
– Geotechnical stability of areas under TSF, WRD, MC Dams
Geotechnical, Mine design and Water management support
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New Liberty: Mining Schedule Highlights
• Updated geotechnical model and slope design
• Production evenly distributed over LOM – mining design has a high level of confidence
• Reserves contained within open pit at depths of 180-220m below surface
• WRD wraps around pit and backfill into Larjor pit
• Annual waste mining rate of 25Mt for four years using mining contractor
LOM Production and Grade
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0
20
40
60
80
100
120
140
Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8
Production + Inferred (koz)Production (koz) - LHSHead Grade (g/t) - RHS
4
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Key Mining Points
• In situ reserves of 924koz gold at 3.4g/t (contained in 8.5mt)
• Pit is 2km long, 420m wide and 220m deep
• Mine life = 8 years
• Total ore mined = 8.5Mt
• Total mined tonnage = 140Mt
• Stripping ratio = 15.5:1
• Mining cost $3.06/t mined*
• Gold produced = 859koz
5
W
E
* Includes cost of fleet
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Experienced Mining Contractor: Banlaw Africa Ltd.
• Combined executive management experience of over 50 years in similar West African environments
• Mining at Bonikro gold mine (Newcrest) in Cote d’Ivoire
• Experience on various projects in Ghana (Gold Fields), Burkina Faso (High River, Bissa), Cote d’Ivoire (Endeavour, Agbaou) and the DRC (Banro, Twangiza)
• Banlaw’s management team are well known to the Aureus management & project team
Mining Contract
• Developed from the detailed AMC mine plan
• All-in cost includes establishment & mobilisation, load & haul, drill & blast, pre-split, RC grade control and fixed costs for the life of mine
• New mining fleet agreed
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Material Movement by Stage
-
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8
Ton
ne
s (M
t)
Material Movement by Stage
Stage 1 Stage 2 Stage 3 Stage 4 Stage 5
Larjor
Marvoe
Latiff Kinjor
2 4 3 1
5 7
Mining •2 km long open pit operation, 220m deep
•Staged mining sequence planned
•High grade (3.4g/t) allows for lower throughput, hence smaller plant – 1.1Mtpa
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Ore Production
-
1.0
2.0
3.0
4.0
5.0
6.0
0.0
0.1
0.1
0.2
0.2
0.3
0.3
0.4
0.4
0.5
Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8
Min
ed O
re G
rade
(Au
g/t)
Min
ed T
onne
s (M
t)
Mined Ore Tonnes and Grade
Mined Ore Tonnes Mined Grade (g/t) Mined Grade (g/t) FS
8
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Waste mining and strip ratio
9
-
10.0
20.0
30.0
40.0
50.0
60.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8
Strip
Rat
io
Min
ed T
onne
s (M
t)
Mined Tonnes and Strip Ratio
Mined Waste Tonnes Mined Ore Tonnes Strip Ratio
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Ounces Produced
-
100
200
300
400
500
600
700
800
900
1,000
0
5
10
15
20
25
30
35
40
45
Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8
Cum
ulat
ive
Oun
ces
Prod
uced
(koz
)
Oun
ces
Prod
uced
(koz
)
Ounces Produced and Cumulative Ounces Produced
Gold Produced (Au oz) Gold Produced (Au oz) FS
Cumulative Ounces Produced FS Cumulative Ounces Produced
10
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Cash flows and revenues
11
-
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8
Cos
t per
Ton
ne M
ined
($ m
illio
ns/t)
Min
ing
Cos
t (U
S$M
)
Mining Cost and Cost Per Tonne Mined
Total Mining Cost Cost Per Tonne Mined
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Aim
• Define mineralisation boundaries and minimise
dilution
• Define mining blocks
Prior to mining
• RC drill programme on 15x15m grid planned
• Drill 1 year’s production in advance, ~ 8,000m/ year
• Reconcile with orebody block model (based on a
30x30m grid)
• Establish detailed distribution of gold and incorporate into mine planning 12
Grade Control
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Production
• RC drilling in dry season in advance of mining
• Sample blastholes (10m benches)
• In pit geological mapping – structures, bleaching, silicification, sulphides, mag sus.
• Reconciliation of grade control work with both orebody model and plant figures
• Marking out of grade blocks (minimum mining width of 2.5m)
• Blast design to separate waste from ore
• Selective mining - 2.5m flitches on 10m benches
• Blending on ROM pad near crusher to ensure steady feed to plant
• High, Medium & Low grade stockpiles and Mineralised waste 13
Grade Control
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Waste Rock Dumps
• The WRD is a wrap-around dump between 30-40m high
• Protection provided below the MCDC dams – placing a barrier between the dams and the pit
• Dumps are flat and cheaper to construct
• Flatter dumps will be easier to rehabilitate and will be visually less obtrusive
• Dumps will help to limit the inflow of surface water into the pit during the rainy season
• Drainage on the dumps will be managed
FS Nov 2012 Waste Dump located to south of Pit
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End of Pre-strip (Year 0)
15
Construction of; haul roads, perimeter safety bund/road.
ROM Pad built up to crusher level Skyway built.
Construction of; Larjor drainage channels. Latkin drainage channel.
Construction of; culverts and flood-ways, permeable bund locations.
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End of Year 1 Mining
16
North, South East and East Dump built up to control surface run-off
Priority dumping in North and North West Dump reduce haulage distances.
Low-grade stockpile area to be built up to pad level with oxide. The oxide can be reclaimed for capping TSF at end-of-mine.
Waste Dump abuts dam walls.
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Outcomes/ Conclusions: • No significant geotechnical risks highlighted • Quality of geotechnical database improved • Improved confidence in the geotechnical model and in slope designs • Likelihood of toppling failure is considered low • Satisfactory Factors of Safety achieved in the calculated slopes • 15m geotechnical berm introduced as additional safety measure • Slope design parameters outcomes:
– Bench face angle 70⁰ & 75⁰ (steepened from 65⁰ in Feasibility study) – Overall slope angle 48⁰ (broadly similar to Feasibility Study) – Local areas of slope de-watering recommended
Geotechnical Data Work completed in 2013
Work undertaken: • New data acquired
– Campaign of targeted drilling into interpreted geological structures (7 holes) – Detailed geotechnical surveys on selected holes (20 holes)
• Structural model of pit updated & 8 domains defined
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Water Management – work completed
• Predominantly rainfall dominated system: Rainfall seasonal with wet season
from July - September. Dewatering system designed to
minimize pit days following storm events
• Surface water management updated based on new waste dump and infrastructure
• Storm event pit inflows revised based on new designs.
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Water Management
• Waste rock dump designed to minimize pit inflows • Dumps profiled to drain water away from pit catchment
• All flows within pit catchment dealt with by in-pit pumps
• Main discharge channel and sedimentation basin developed by optimizing natural drainage to south
• Groundwater investigation completed
• Numerical groundwater flow model developed
• Groundwater pit inflows updated
• Groundwater drawdown updated
• Staged dewatering strategy and design
• Depressurization modelling completed
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Final Pit Number of Sykes HH220i Pumps
Sump Pumps Transfer Station Pumps
Larjor High Head Pump or inclined dewatering bore(s) used following backfill of Larjor Pit
Latiff 1 5
Kinjor 1
Marvoe 1 1
NB One extra sump pump will be required as a standby
Staged Pit Dewatering Strategy and Design: Phased plan for pump locations, sump locations and pipelines
Year 1
Year 2
Year 3
Year 4
Year 6
Year 8
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Groundwater Modelling Drawdown and Inflows
• 3D numerical groundwater flow modelling completed • Modelling estimates groundwater pit inflows and regional groundwater
level drawdown • Groundwater pumping will generally range between 15 to 40L/s; less
than 10% of the 210-240L/s capacity of the sump pumps which are required to deal with storm run-off
21
GW Model Final Pit Drawdown GW Model Pit Inflows
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Conclusions
• Mining to be advanced in dry season, creating more flexibility in wet season
• Mining rates and pit design optimised to minimise costs and maximise ore availability
• Good grade control key to maximising recovery from ore
• Increased geotechnical confidence - managing against pit failures
• Surface water flows managed through runoffs and pumping
• Groundwater managed through pumping, drain holes and pit design
• Waste dump design minimises haulage costs, aids safety, water management and restoration potential
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Thank you
www.aureus-mining.com